modellistaction.java

用jbuilder写的源程序

/**
 * Copyright 2003-2006 the original author or authors.
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

package com.jdon.strutsutil;

import java.util.ArrayList;
import java.util.Collection;
import java.util.List;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.struts.action.ActionForm;
import org.apache.struts.action.ActionForward;
import org.apache.struts.action.ActionMapping;

import com.jdon.controller.model.Model;
import com.jdon.controller.model.ModelIF;
import com.jdon.controller.model.PageIterator;
import com.jdon.model.ModelKey;
import com.jdon.util.Debug;

/**
 * batch query action
 *
 * @author banq
 */
public abstract class ModelListAction  extends ModelBaseAction {

  private final static String module = ModelListAction.class.getName();

  public ActionForward execute(ActionMapping actionMapping,
                               ActionForm actionForm,
                               HttpServletRequest request,
                               HttpServletResponse response) throws
      Exception {

    intContext(this.getServlet().getServletContext());
   

    int start = 0;
    int count = 30;

    String startStr = request.getParameter("start");
    if ( (startStr != null) && (startStr.length() != 0)) {
      start = Integer.parseInt(startStr);
    }
    String countStr = request.getParameter("count");
    if ( (countStr != null) && (countStr.length() != 0)) {
      count = Integer.parseInt(countStr);
    }
    

    ModelListForm listForm = getModelListForm(actionMapping, actionForm, request);
    listForm.setStart(start);

    PageIterator pageIterator = getPageIterator(request, start, count);
	if (pageIterator != null) {// by pageIterator
		if (pageIterator.isElementsTypeIsKey()){
			setModellistByKey(listForm, pageIterator, request);	
		}else{
			setModellistByModel(listForm, pageIterator, request);	
		}		
	} else {
		Debug.logError("getPageIterator not be implemented, you must implement either of them ", module);
		listForm.setList(new ArrayList());
	}
	
    listForm.setOneModel(setupOneModelIF(request));
    customizeListForm(actionMapping, actionForm, request, listForm);

    if (actionMapping.findForward(FormBeanUtil.FORWARD_SUCCESS_NAME) == null)
      Debug.logError(
          "not found the forward name '" + FormBeanUtil.FORWARD_SUCCESS_NAME +
          "' in struts-config.xml", module);

    return actionMapping.findForward(FormBeanUtil.FORWARD_SUCCESS_NAME);
  }
  
  private void setModellistByKey(ModelListForm listForm,
			PageIterator pageIterator, HttpServletRequest request) {
		Collection c = null;
		try {
			listForm.setAllCount(pageIterator.getAllCount());
			if (pageIterator.getCount() != 0)
				listForm.setCount(pageIterator.getCount());// for block
															// pageIterator
			c = getModelList(request, pageIterator);
			Debug.logVerbose(
					"[JdonFramework] listForm 's property: getList size is "
							+ c.size(), module);
			pageIterator.reset();		
		} catch (Exception e) {
			Debug.logError(" setModellistByKey error " + e, module);
			c = new ArrayList();
		}
		listForm.setList(c);
  }
  
  /* the elements in pageIterator is Model type
  * we directly add them in result
  */ 
  private void setModellistByModel(ModelListForm listForm,
			PageIterator pageIterator, HttpServletRequest request) {
		Collection c = null;
		try {
			listForm.setAllCount(pageIterator.getAllCount());
			if (pageIterator.getCount() != 0)
				listForm.setCount(pageIterator.getCount());
			c = new ArrayList(pageIterator.getSize());
			while (pageIterator.hasNext()) {
				Object o = pageIterator.next();
				if ( o != null)
					c.add(o);
			}
			Debug.logVerbose(
					"[JdonFramework] listForm 's property: getList size is "
							+ c.size(), module);
			pageIterator.reset();		
		} catch (Exception e) {
			Debug.logError(" setModellistByModel error " + e, module);
			c = new ArrayList();
		}
		listForm.setList(c);
  }

  /**
   * 获得ModelListForm实例
   *
   * @param actionMapping
   * @param actionForm
   * @param request
   * @return
   * @throws java.lang.Exception
   */
  protected ModelListForm getModelListForm(ActionMapping actionMapping,
                                        ActionForm actionForm,
                                        HttpServletRequest request) throws
      Exception {
    ModelListForm modelListForm = null;
    if (actionForm == null){
      modelListForm = new ModelListForm();
      FormBeanUtil.saveActionForm(modelListForm, actionMapping, request);
    }else if (actionForm instanceof ModelListForm)
      modelListForm = (ModelListForm) actionForm;

    if (modelListForm == null)
      throw new Exception(
          "not found the bean of com.jdon.strutsutil.ModelListForm");
    else
      return modelListForm;

  }

  /**
   * 根据PageIterator中ID集合，获得相应的Model集合
   * @param request
   * @param pageIterator
   * @return Model集合
   * @throws java.lang.Exception
   */
  protected List getModelList(HttpServletRequest request,
                            PageIterator pageIterator) throws Exception {
    List list = new ArrayList(pageIterator.getSize());
    ModelIF model = null;
    Class modelClass = null;
    while (pageIterator.hasNext()) {
      Object dataKey = pageIterator.next();
      if ( (modelClass == null) || (!isEnableCache())) {
        Debug.logVerbose("[JdonFramework] getCache from db. " , module);
        model = fetchModel(request, dataKey);
        if (model != null)
          modelClass = model.getClass();
        else
          continue;        
      } else {
        //首先从缓存中获取
        ModelKey modelKey = new ModelKey(dataKey, modelClass);
        model = modelManager.getCache(modelKey);
        if (model == null) {
          model = fetchModel(request, dataKey);
          modelManager.addCache(modelKey, model);
        }
      }
      if (model != null)
          list.add(model);
    }    
    return list;
  }
  

  /**
   * 定制ModelListForm
   *
   * 缺省ModelListForm是只有一个List，包含一种Model集合
   * 有的应用可能是两种Model集合，可以继承ModelListForm实现Map-backed ActionForms
   * 再继承本Action，实现本方法。
   *
   * @param actionMapping
   * @param actionForm
   * @param request
   * @param modelListForm
   * @throws java.lang.Exception
   */
  public void customizeListForm(ActionMapping actionMapping,
                                    ActionForm actionForm,
                               HttpServletRequest request,
                              ModelListForm modelListForm ) throws Exception{


  }


  /**
   * 
   * decide if enable cacche?
   * the sub-class can unable cache by overrid this method
   * @param enable
   */
  protected boolean isEnableCache() {
    return true;
  }

  private ModelIF fetchModel(HttpServletRequest request, Object dataKey) throws
      Exception {
    if (dataKey == null) return null;
    ModelIF model = null;
    try {
      model = findModelIFByKey(request, dataKey);
      if (model == null){                    
          Debug.logWarning("[JdonFramework] the model is null for the primary key=" + dataKey+" and data type=" + dataKey.getClass().getName()+ ", reasons:", module);
          Debug.logWarning("[JdonFramework] 1. maybe the data in database wae deleted ", module);          
          Debug.logWarning("[JdonFramework] 2. a error occured in the findModelByKey mehtod of the class "+ this.getClass().getName(), module);
      }
    } catch (Exception ex) {
      Debug.logError(ex, module);
    }
    return model;
  }

  protected ModelIF setupOneModelIF(HttpServletRequest request) {
      return setupOneModel(request);
   }
  
  protected Model setupOneModel(HttpServletRequest request){
      return null;
  }


  /**
   * get a PageIterator from the service
   *
   * @param request HttpServletRequest
   * @param start int
   * @param count int
   * @return PageIterator
   */
  public abstract PageIterator getPageIterator(HttpServletRequest request,
                                               int start,
                                               int count);

  /**
   * obtain a Model instance from service layer
   *
   * @param request HttpServletRequest
   * @param key Object the primary key of the Model 
   * @return ModelIF   return the Model object from service layer
   */
  public  ModelIF findModelIFByKey(HttpServletRequest request, Object key){
      return findModelByKey(request, key);
  }
     
  /**
   * for old version 
   */
  public Model findModelByKey(HttpServletRequest request, Object key){
	  return null;
  }
  
  


}